In the past, many manual coaxial switches have been designed to connect a first high frequency coaxial line to other individual transmission lines. Such a device is shown in the Concelman U.S. Pat. No. 3,010,080. The disadvantage of this design is the parasitic inductance and capacitance interaction between the wheel contacts which cause the signal to arc just before contact. Therefore, the wheels will pit which will shorten the life of the switch considerably.
The wheel contact design also limits the actual contact area between the wheel, the secondary contacts and the input contacts to a very small area. This small contact area impedes the effectiveness of the switch in medium andhigh power ranges.
Various switch designs, such as the Concelman patent, have pinned pivot points on the handles of their switching assembly, thus permitting chips from the handle to accumulate in the switching contact area and create high frequency shorting of the signal from any one of the contacts to the body ground.
Further, designs have been proposed with reciprocating or slide action. Such a design in shown by O'Hara in U.S. Pat. No. 1,340,788. However, this switch tends to generate unwanted cross-interference between elements.
Another disadvantage of prior designs is that they permit moisture to enter the switch and remain in the contact area when used in high humidity environments.